Many regions of the world today use irrigation systems for artificial distribution of water. One of the most widely used irrigation systems, particularly where water is not abundant or plentiful, is a sprinkler system wherein one or more sprinkler units are positioned about a land area for distributing water over the surface of the land area. Such systems are widely used in most developed countries for a variety of applications including the irrigation of lawns, golf courses, playing fields and field crops.
Impact sprinklers are generally well known in the art and have been used for many years. There are essentially two broad varieties or types of impact sprinklers. The first type is the open or common riser mounted sprinkler unit which is attached to the end of a riser stem or pipe formed with a water conduit. This type of sprinkler is most often used in open areas such as flower beds or the like which do not require close trimming. These units extend upwardly from the surface and are somewhat obtrusive and unattractive. Consequently, they are used in areas where the units are not readily observed nor require maintenance with lawnmowers. The second type of impact sprinkler is a similar type of unit mounted within a housing which is, in turn, buried beneath the surface of the ground so that the sprinkler generally provides a pop-up unit. These impact sprinklers are most often used in lawn settings, and are mounted within housings or wells that are buried underground. The top of the housings are substantially flush with the ground surface so that open areas such as lawns may be easily landscaped or mowed. When water is supplied to the sprinklers, they pop-up or rise above their housings and the ground surface. In this fashion, the sprinklers remain out of sight until activated. However, the housings for this type of sprinkler, which are designed with an open-case to accommodate standard rotating impact sprinkler arms, tend to become filled with debris such as dirt, grass clippings and the like. Any of the above hamper the ability of the sprinkler to pop-up and to retract, or to effectively drive the sprinkler.
Another common type of irrigation device is known in the art as a gear driven sprinkler. Gear-driven sprinklers have rotating nozzles effectively driven by various gear driving mechanisms which are activated by water supplied to the sprinkler. These sprinklers provide an advantage in that their housings are enclosed by design thus avoiding the problems associated with the open or well-type design of an impact sprinkler. However, it has been observed that gear-driven sprinklers are frequently subject to failure due to debris becoming engaged or lodged within the gear drive mechanism. Many designs are also plagued with a relatively limited watering range due in part to the general power-draining design of the gear driving mechanisms.
The sprinkler literature includes numerous patents relating to variations of sprinkler units known in the art. U.S. Pat. No. 3,602,431 entitled A SPRINKLER DEVICE FOR FLUID DISTRIBUTION (Lockwood) is directed to a sprinkler for distributing water comprising a body, a sprinkler head rotatably connected to the body, a fluid flow interrupter for providing controlled bursts of fluid in the stream of fluid exiting from the sprinkler head, an interrupter drive, a drive means including a free rotating ball for driving the sprinkler head, and reversing means for reversing the direction of movement of the sprinkler head. U.S. Pat. No. 3,765,608 entitled AUTOMATIC INTERMITTENT BREAK-UP DEVICE (Lockwood) is directed to a sprinkler with an automatic intermittent break-up device repeatedly movable toward the center of the fluid stream exiting a nozzle to a first position to increase the break-up of the stream and movable away from the center of the fluid stream exiting the nozzle to a second position to decrease the break-up to provide more desired distribution of fluid on the surface area. U.S. Pat. No. 3,930,617 entitled IMPACT SPRINKLER (Dunmire) is directed to an impact sprinkler which uses a plastic water deflector having a number of cooperating water deflecting surfaces which improve the overall water distribution pattern of the sprinkler; the particular configuration provided for allowing the water deflector to pivot back and forth. U.S. Pat. No. 4,055,304 entitled AUXILIARY BRAKING MEANS FOR IMPACT ARM SPRINKLERS (Munson) is directed to an impact type rotary sprinkler including a rotatable body and nozzle, an impact arm which oscillates responsive to the kinetic energy of the fluid discharge stream and a primary spring which stores the rotational energy of the oscillating arm rotating to impact against the housing and impart an increment of rotation thereto. U.S. Pat. No. 4,103,828 entitled ROTARY SPRINKLER IMPACT ARM SPRING ADJUSTMENT (Ridgway) is directed to a rotary sprinkler with structure for adjusting the force applied to the impact arm by the impact arm spring, viz. a laterally directed nozzle cooperating with the arm to rotate the nozzle and an impact arm on a shaft extending above the nozzle. The arm is mounted within a cage extending above the nozzle. U.S. Pat. No. 4,164,324 entitled SPRINKLER HEAD WITH IMPROVED INTEGRAL IMPACT ARM AND ANTI-BACKSPLASH DRIVE SPOON (Bruninga) is directed to a part-circle rotary sprinkler head having an improved anti-backsplash drive spoon integrally formed as a part of the impact arm. U.S. Pat. No. 4,182,494 entitled ANTISIDE SPLASH DRIVE ARM FOR AN IMPACT DRIVE SPRINKLER (Wichman) is directed to an impact sprinkler of the full or part circle type with an anti side splash drive arm. Despite these and other known sprinkler designs, there is a need for an irrigation sprinkler that incorporates the advantages provided by both impact and gear-driven sprinkler designs.